In the related art, there is known, for example, a touch panel system disclosed in PTL 1 as a touch panel system that detects the position of the touch of a touch pen on a touch panel which has electrostatic capacitances formed at each intersection of a plurality of first signal lines and a plurality of second signal lines.
The touch panel system disclosed in PTL 1 includes a plurality of electronic pens, a panel main body that includes a touch face on which a touch operation is performed by the electronic pens and a finger and in which a plurality of transmission electrodes that runs parallel to each other and a plurality of reception electrodes that runs parallel to each other are arranged into a lattice, a transmission unit that applies a drive signal to the transmission electrodes, a reception unit that receives a response signal which is output from the reception electrodes in response to the drive signal applied to the transmission electrodes and outputs detection data for each intersection of the electrodes, and a control unit that detects the position of a touch on the basis of the detection data which is output from the reception unit, in which the transmission unit applies a pen synchronization signal that synchronizes the transmission and reception of a pen identifiable signal between the electronic pens and the reception unit to the transmission electrodes, the electronic pens transmit the pen identifiable signal to the reception electrodes in response to the detection of the pen synchronization signal of the transmission electrodes at the time of a touch operation, and the control unit, on the basis of the pen synchronization signal that the reception unit receives through the reception electrodes, identifies a pointed object on which a touch operation is performed.
According to this configuration, a plurality of electronic pens can be used because each electronic pen transmits the pen identifiable signal to the reception electrodes in response to the detection of the pen synchronization signal from the transmission electrodes at the time of a touch operation and because the control unit, on the basis of the pen synchronization signal that the reception unit receives through the reception electrodes, identifies the electronic pen that performs the touch operation.
The touch panel system disclosed in PTL 1 has a problem in that it is not possible to remove an erroneous signal that is generated by electromagnetic noise which is caused by the touch of a hand, a finger, and the like of a human body, which receives electromagnetic noise when touching the electronic pen, on a touch panel and which is generated at a position different from the position of the touch.
Therefore, in order to resolve this problem, the applicant of the present application suggests a touch panel system disclosed in PTL 2.
The touch panel system disclosed in PTL 2 includes a touch panel that has electrostatic capacitances formed at each intersection of a plurality of first signal lines and a plurality of second signal lines, a touch pen, and a touch panel controller, in which the touch panel controller, when repeatedly performing switched driving such that the plurality of first signal lines is driven to output charge signals based on each electrostatic capacitance from each of the second signal lines during a first signal line drive period and such that the plurality of second signal lines is driven to output charge signals based on each electrostatic capacitance from each of the first signal lines during a second signal line drive period, detects the position of a touch on the basis of a change in electrostatic capacitance due to the touch pen when the touch pen touches the touch panel.
In the touch position detecting method in the touch panel system having the above configuration, when the touch pen touches the touch panel, a detected position in the first signal line drive period and a detected position in the second signal line drive period are represented at the same position. Meanwhile, an erroneous signal due to noise that is caused by the touch of a hand, a finger, and the like of a human body, which receives electromagnetic noise, on the touch panel and that is generated at a position different from the position of the touch, even when represented in the first signal line drive period by switching driving of the first signal lines and the second signal lines, is not represented at the same position in the second signal line drive period.
Therefore, it is possible to distinguish a signal of a touch of the touch pen and an erroneous signal due to noise and easily remove the erroneous signal due to noise.